Fix functions to detect eclipse (#75)

* Update TPM_Didymos.jl

* Update energy_flux.jl

- Change the names of functions (`binary_is_aligned`)

* Update energy_flux.jl

* Update energy_flux.jl

Fix `find_eclipse!`

* Update energy_flux.jl

* Update energy_flux.jl

* Update energy_flux.jl

* Rename `find_eclipse!` to `mutual_shadowing!`

src/TPM.jl

@@ -267,8 +267,8 @@ function run_TPM!(btpm::BinaryTPM, ephem, savepath)
         update_flux_scat_single!(btpm)
         update_flux_rad_single!(btpm, nₜ)
 
-        ## Mutual-shadowing
-        find_eclipse!(btpm, r☉₁, sec_from_pri, R₂₁)
+        ## Mutual-shadowing (eclipse)
+        mutual_shadowing!(btpm, r☉₁, sec_from_pri, R₂₁)
 
         ## Mutual-heating
         #

src/energy_flux.jl

@@ -270,57 +270,141 @@ end
 #                  Eclipse of binary asteroid
 # ****************************************************************
 
-"""
-The secondary is within the critical angle to detect an eclipse event.
-"""
-function eclipse_is_possible(btpm::BinaryTPM, sun_from_pri, sec_from_pri)
-
-    R₁ = maximum_radius(btpm.pri.shape)
-    R₂ = maximum_radius(btpm.sec.shape)
-    θ_crit = asin((R₁ + R₂) / norm(sec_from_pri))
-
-    r̂☉ = SVector{3}(normalize(sun_from_pri))
-    r̂ₛ = SVector{3}(normalize(sec_from_pri))
-    θ = acos(r̂☉ ⋅ r̂ₛ)  # Angle of Sun-Primary-Secondary
-
-    θ_crit < θ < π - θ_crit ? false : true
-end
-
-
-"""
-    find_eclipse!(shapes, sun_from_pri, sec_from_pri, R₂₁)
 
-- `shapes`
-- `sun_from_pri`
-- `sec_from_pri` : Position of the secondary relative to primary
-- `R₂₁`          : Rotation matrix from secondary to primary
 """
-function find_eclipse!(btpm::BinaryTPM, sun_from_pri, sec_from_pri, R₂₁)
+    mutual_shadowing!(btpm::BinaryTPM, r☉, rₛ, R₂₁)
 
-    r̂☉ = SVector{3}(normalize(sun_from_pri))
-    # r̂ₛ = SVector{3}(normalize(sec_from_pri))
-    rₛ = SVector{3}(sec_from_pri)
+Detect eclipse events between the primary and secondary, and update the solar fluxes of the faces.
 
-    eclipse_is_possible(btpm, r̂☉, rₛ) == false && return
-
-    for i in eachindex(btpm.pri.shape.faces)
-        btpm.pri.flux[i, 1] == 0 && continue                        # something wrong?
-        A₁, B₁, C₁ = btpm.pri.shape.nodes[btpm.pri.shape.faces[i]]  # △ABC in primary
-        G₁ = btpm.pri.shape.face_centers[i]                         # Center of △ABC in primary
-
-        for j in eachindex(btpm.sec.shape.faces)
-            btpm.sec.flux[j, 1] == 0 && continue                        # something wrong?
-            A₂, B₂, C₂ = btpm.sec.shape.nodes[btpm.sec.shape.faces[j]]  # △ABC in secondary
-            G₂ = btpm.sec.shape.face_centers[j]                         # Center of △ABC in secondary
+# Arguments
+- `btpm` : Thermophysical model for a binary asteroid
+- `r☉`   : Position of the sun relative to the primary       (NOT normalized)
+- `rₛ`   : Position of the secondary relative to the primary (NOT normalized)
+- `R₂₁`  : Rotation matrix from secondary to primary
+"""
+function mutual_shadowing!(btpm::BinaryTPM, r☉, rₛ, R₂₁)
+
+    shape1 = btpm.pri.shape
+    shape2 = btpm.sec.shape
+    r̂☉ = normalize(r☉)
+
+    θ = acos((r☉ ⋅ rₛ) / (norm(r☉) * norm(rₛ)))  # Angle of Sun-Primary-Secondary
+
+    R₁ = maximum_radius(shape1)
+    R₂ = maximum_radius(shape2)
+    R₁ < R₂ && error("Error: The primary radius is smaller than the secondary.")
+
+    θ₊ = asin((R₁ + R₂) / norm(rₛ))  # Critical angle at which partial ecripse can occur
+    θ₋ = asin((R₁ - R₂) / norm(rₛ))  # Critical angle at which total ecripse can occur
+
+    #### Partital eclipse of the primary ####
+    if 0 ≤ θ < θ₊
+        r₂ = minimum_radius(shape2)
+
+        for i in eachindex(shape1.faces)
+            G₁ = shape1.face_centers[i]  # Center of △A₁B₁C₁ in primary
+            n̂₁ = shape1.face_normals[i]  # Normal vector of △A₁B₁C₁ in primary
+
+            ## if △A₁B₁C₁ is NOT facing the sun
+            if r̂☉ ⋅ n̂₁ < 0
+                btpm.pri.flux[i, 1] = 0
+                continue
+            end
+
+            d₁ₛ = rₛ - G₁                   # Vector from △A₁B₁C₁ to secondary center
+            θ₁ = acos(r̂☉ ⋅ normalize(d₁ₛ))  # Angle of Sun-△A₁B₁C₁-Secondary
+            θ_R₂ = asin(R₂ / norm(d₁ₛ))     # Critical angle related to the maximum radius of the secondary
+            θ_r₂ = asin(r₂ / norm(d₁ₛ))     # Critical angle related to the minimum radius of the secondary
+
+            ## In the secondary shadow
+            if θ₁ < θ_r₂
+                btpm.pri.flux[i, 1] = 0
+                continue
+            ## Out of the secondary shadow
+            elseif θ₁ > θ_R₂
+                continue
+            else
+                for j in eachindex(shape2.faces)
+                    A₂, B₂, C₂ = shape2.nodes[shape2.faces[j]]  # △A₂B₂C₂ in secondary
+                    G₂ = shape2.face_centers[j]                 # Center of △A₂B₂C₂
+                    n̂₂ = shape2.face_normals[j]                 # Normal vector of △A₂B₂C₂
 
-            ## Transform coordinates from secondary- to primary-fixed frame
-            A₂ = R₂₁ * A₂ + rₛ
-            B₂ = R₂₁ * B₂ + rₛ
-            C₂ = R₂₁ * C₂ + rₛ
+                    ## Transformation from secondary to primary frame
+                    A₂ = R₂₁ * A₂ + rₛ
+                    B₂ = R₂₁ * B₂ + rₛ
+                    C₂ = R₂₁ * C₂ + rₛ
+                    G₂ = R₂₁ * G₂ + rₛ
+                    n̂₂ = R₂₁ * n̂₂
+
+                    d₁₂ = G₂ - G₁  # Vector from primary face i to secondary face j
+
+                    ## if △A₁B₁C₁ and △A₂B₂C₂ are facing each other
+                    if d₁₂ ⋅ n̂₁ > 0 && d₁₂ ⋅ n̂₂ < 0
+                        if raycast(A₂, B₂, C₂, r̂☉, G₁)
+                            btpm.pri.flux[i, 1] = 0
+                            break
+                        end
+                    end
+                end
+            end
+        end
+
+    #### No eclipse ####
+    # elseif θ₊ ≤ θ < π - θ₊
+    # Do nothing
+
+    #### Partial eclipse of the secondary ####
+    elseif π - θ₊ ≤ θ < π - θ₋
+        r₁ = minimum_radius(shape1)
+
+        for j in eachindex(shape2.faces)
+            G₂ = shape2.face_centers[j]  # Center of △A₂B₂C₂ in secondary
+            n̂₂ = shape2.face_normals[j]  # Normal vector of △A₂B₂C₂ in secondary
+
+            ## Transformation from secondary to primary frame
             G₂ = R₂₁ * G₂ + rₛ
-
-            raycast(A₂, B₂, C₂, r̂☉, G₁) && (btpm.pri.flux[i, 1] = 0)  # something wrong?
-            raycast(A₁, B₁, C₁, r̂☉, G₂) && (btpm.sec.flux[j, 1] = 0)  # something wrong?
+            n̂₂ = R₂₁ * n̂₂
+
+            ## if △A₂B₂C₂ is NOT facing the sun
+            if r̂☉ ⋅ n̂₂ < 0
+                btpm.sec.flux[j, 1] = 0
+                continue
+            end
+
+            d₂ₚ = - G₂                      # Vector from △A₂B₂C₂ to primary center (origin)
+            θ₂ = acos(r̂☉ ⋅ normalize(d₂ₚ))  # Angle of Sun-△A₂B₂C₂-Primary
+            θ_R₁ = asin(R₁ / norm(d₂ₚ))     # Critical angle related to the maximum radius of the primary
+            θ_r₁ = asin(r₁ / norm(d₂ₚ))     # Critical angle related to the minimum radius of the primary
+
+            ## In the primary shadow
+            if θ₂ < θ_r₁
+                btpm.sec.flux[j, 1] = 0
+                continue
+            ## Out of the primary shadow
+            elseif θ₂ > θ_R₁
+                continue
+            else
+                for i in eachindex(shape1.faces)
+                    A₁, B₁, C₁ = shape1.nodes[shape1.faces[i]]  # △A₁B₁C₁ in primary
+                    G₁ = shape1.face_centers[i]                 # Center of △A₁B₁C₁
+                    n̂₁ = shape1.face_normals[i]                 # Normal vector of △A₁B₁C₁
+
+                    d₁₂ = G₂ - G₁  # Vector from primary face i to secondary face j
+
+                    ## if △A₁B₁C₁ and △A₂B₂C₂ are facing each other
+                    if d₁₂ ⋅ n̂₁ > 0 && d₁₂ ⋅ n̂₂ < 0
+                        if raycast(A₁, B₁, C₁, r̂☉, G₂)
+                            btpm.sec.flux[j, 1] = 0
+                            break
+                        end
+                    end
+                end
+            end
         end
+
+    #### Total eclipse of the secondary ####
+    elseif π - θ₋ ≤ θ < π
+        btpm.sec.flux[:, 1] .= 0
     end
 end
+

test/TPM_Didymos.jl

@@ -41,9 +41,10 @@
     end
 
     ##= Ephemerides =##
-    et_begin = SPICE.utc2et("2027-02-18T00:00:00")
-    et_end   = SPICE.utc2et("2027-02-19T00:00:00")
-    step     = 300
+    P        = SPICE.convrt(AsteroidThermoPhysicalModels.DIDYMOS[:P], "hours", "seconds")  # Rotation period of Didymos
+    et_begin = SPICE.utc2et("2027-02-18T00:00:00")                                         # Start time of TPM
+    et_end   = et_begin + 10P                                                              # End time of TPM
+    step     = P / 72                                                                      # Time step of TPM
     et_range = et_begin : step : et_end
     @show length(et_range)